1. Field of the Invention
The present invention relates to a polypeptide having an enzymatic activity, more particularly, to a polypeptide having a xcex2-fructofuranosidase activity obtainable by the expression of a microbial gene.
2. Description of the Prior Art Fructofuranosyl-transferred saccharides such as xylosylfructoside and lactosucrose, which have strong anticariogenic activities and growth promoting activities for bifid bacteria, are highlighted as the latest sweeteners substitutable for sucrose in the food and pharmaceutical industries. The fructofuranosyl-transferred saccharides are usually produced using xcex2-fructofuranosidases by contacting the enzymes with sucrose and amylaceous saccharides or lactose as materials. xcex2-Fructofuranosidases derived from microorganisms of the genera Bacillus and Arthrobacter have been widely used. However, the enzyme productivity of these microorganisms is relatively low, resulting in the requirement of a considerably large-scale culture of the microorganisms as a disadvantage.
The recent progress of recombinant DNA technology is outstanding. Even an enzyme, whose total amino acid sequence is not revealed, can be obtained with relative ease in a desired amount by preparing a recombinant DNA containing a DNA which encodes the enzyme, introducing the recombinant DNA into microorganisms or cells of plants and animals to obtain transformants, and culturing the transformants in nutrient culture media, if only a gene encoding the enzyme were isolated and the nucleotide sequence were decoded. In view of the foregoing, it is urgently required to obtain and reveal a gene encoding a xcex2-fructofuranosidase.
In view of these circumstances, the first object of the present invention is to provide a polypeptide having a xcex2-fructofuranosidase activity, which can be easily produced in a relatively-large scale by applying the recombinant DNA technology.
The second object of the present invention is to provide a DNA encoding the polypeptide.
The third object of the present invention is to provide a transformant into which the DNA is introduced.
The fourth object of the present invention is to provide a process for producing the polypeptide using the transformant.
The fifth object of the present invention is to provide a method for fructofuranosyl transfer by using the polypeptide.
To overcome the above objects, the present inventors energetically studied and found a polypeptide which has a xcex2-fructofuranosidase activity and the amino acid sequences of SEQ ID NOs:1 and 2 in whole or in part as a partial amino acid sequence and is easily obtainable in a desired amount by the expression of a microbial gene.
The first object of the present invention is solved by a polypeptide which has a xcex2-fructofuranosidase activity and the amino acid sequences of SEQ ID NOs:1 and 2 in whole or in part as a partial amino acid sequence and is obtainable by the expression of a microbial gene.
The second object of the present invention is solved by a DNA encoding the polypeptide.
The third object of the present invention is solved by a transformant into which the DNA is introduced.
The fourth object of the present invention is solved by a process for producing the polypeptide comprising steps of culturing the transformant and collecting the produced polypeptide from the culture.
The fifth object of the present invention is solved by a method for fructofuranosyl transfer comprising a step of reacting a fructofuranosyl donor with a fructofuranosyl acceptor in the presence of the polypeptide.